Abstract: In order to analyze smoke spread in the case of automobile fire in the inclined tunnel with curvature, a full-size model of the entrance of Honggu tunnel in Nanchang was established. Numerical simulation of tunnel fires under different wind speeds and different heat release rates of fire source was carried out by using Fluent software, and the critical wind speed to suppress the adverse flow of smoke was investigated. The reliability of numerical simulation is verified by comparing the results with empirical formulae from other scholars. The results show that the existence of slope causes more smoke to spread towards the uphill direction, if wind speed of longitudinal ventilation is too small, it will have a negative effect on the spread of smoke, if wind speed reaches or exceeds the critical wind speed, control effect of smoke is quite good, if wind speed reaches the critical wind speed, asymmetrical distribution of temperature in cross section of tunnel appears due to curvature of tunnel, if heat release rate of tunnel fire is 5, 10 and 20 MW, the critical wind speed is approximately 2.0, 2.5 and 3.0 m/s, respectively. The simulation results are similar to the variation trend of values calculated by empirical formulae.